Internal combustion engines use oil for lubrication and cooling of various internal components. Oil is typically circulated through various engine components with the help of an oil pump. Engine oil pumps are usually driven by gears that are connected to a rotating engine component, for example, a crankshaft, or a camshaft.
A typical engine oil pump has a sump accumulator for oil. A pool of oil is usually collected in a reservoir that is near a low point of the engine. Oil circulated by the oil pump through engine components usually collects back into the oil reservoir. Engines typically have their oil reservoirs in cavities contained in separate pieces that are connected to the engine's crankcase. These pieces, or oil pans, usually sealably connect to the bottom of a crankcase.
Oil pans for internal combustion engines tend to be large components that cover an entire lower opening of an engine's crankcase. As such, they usually have large flat surfaces that span the width and length of the engine. These large flat surfaces often tend to resonate during operation of the engine, and either generate or relay noise during operation of the engine. Noise generation or transmission is usually an undesired attribute to an engine's operation, and there have been various methods used in the past to dampen and/or reduce the noise coming from an engine's oil pan.
One method used in the past for noise reduction of oil pans, is use of metal-polymer-metal (MPM) sheets. An MPM sheet material, for example, a material available in the market under the trade name PCX-9 Quiet Steel™ manufactured by MSC Laminates and Composites Inc., may be made of metal outer skins and a 0.001″ (0.025 mm) thick viscoelastic polymer core. One disadvantage of MPM materials is their shapeability and flexibility in designing their shapes because most MPM oil pans are made by use of a drawing process. MPM oil pans do not lend themselves well for situations where there is little space available for packaging the oil pan around surrounding vehicle components because of the limitations to their shape.
In situations where there is little space available for packaging an oil pan, many engines designs employ metal castings for forming a more intricate shape for the oil pan. Cast-metal oil pans tend to be heavier and more expensive to manufacture, and offer little sound insulation because of their rigidity. Past methods used for sound insulation of cast oil pans have included iso-mounting the oil pan to the engine, covering the oil pan with a sound absorbing material, or trying to design-in less flat surfaces. All these methods have been partly effective in their sound insulating effectiveness, but add cost and complexity to the engine design.
Accordingly, there is a need for an oil pan for an internal combustion engine that has good sound insulation or absorption characteristics, and is flexible in its design shape capabilities. Similarly, there is a need for a valve cover for an internal combustion engine that has good sound insulation or absorption characteristics, and is flexible in its design shape capabilities.